The Impact of Thiazides and Potassium Citrate on Bone Mineral Density Evaluated by CT Scan in Stone Formers

Introduction: Thiazides and citrate prevent kidney stones and improve bone mineral density (BMD). The objective of this study was to opportunistically utilize the noncontrast CT (NCCT) scan used for stone detection to identify those with low BMD and follow the impact of potassium citrate and thiazides on longitudinal BMD measurements. Materials and Methods: A retrospective analysis was performed on 299 kidney stone patients treated with thiazides and/or potassium citrate for a minimum of 1 year. For each patient, BMD was estimated at L1 with CT attenuation measured in HU. A level of 160 HU was chosen to distinguish normal from low BMD. Pairwise t-test was used to compare the continuous outcomes before and after treatment for the whole cohort and the low BMD subgroup. Linear regression was performed to find if any association exists between the duration of follow-up and the changes in HU. A matched pair t-test was performed to compare among the medications used and the impact of their doses on the HU outcomes. Results: Patients with low BMD (HU <160) comprised (n = 186, 62.2%) the cohort. A total of 16.1% normalized after 1 year of treatment and 68% had an increase in HU. The mean change in HU was 8.6 (p = 0.0001). Linear regression demonstrated no association between the duration of treatment and the HU changes (p = 0.64). Hydrochlorothiazide (HCTZ) 50 mg was more effective at improving BMD (HU +19.7, p = 0.04) compared with 25 mg (+2.9) or 12.5 mg (HU +6.4). Majority of the low BMD subgroup were either postmenopausal women (n = 88) or men with age older than 60 (n = 74) and both showed a significant increase in HU (3.125, 10.731), p-value (0.0453, 0.0007), respectively. Conclusion: Stone health and bone health are synergistic. The impact of thiazides and citrates on BMD can be monitored opportunistically with the NCCT scan.